Septoria and Stagonospora Diseases of Cereals - CIMMYT ...

38
Session 1 — J.M. Krupinsky and B.J. Steffenson
were identified on 55, 51, and 10%
of the leaf sections, respectively.
Using the number of leaf sections
infected with a particular fungus as
an indicator of the relative
importance of a fungus, the most
common diseases making up the
leaf-spot disease complex on barley
in North Dakota were in
descending order of importance net
blotch, spot blotch, septoria
speckled leaf blotch, and
stagonospora avenae leaf blotch.
This ranking was similar to those in
Saskatchewan, Canada, north of
western North Dakota, where D.
teres was considered the most
common leaf spotting pathogen,
followed by B. sorokiniana, which
was more common than Septoria
spp. (Fernandez et al., 1999). In
Manitoba, Canada, north of eastern
North Dakota, leaf spot diseases
were considered to cause minimal
damage in 1998. Drechslera teres and
B. sorokiniana were found in 90-93%
of the barley fields and S. passerinii
was recovered in 22% of the fields
(Tekauz et al., 1999).
Two of these diseases, spot
blotch and stagonospora avenae
leaf blotch, are usually minor
diseases on wheat in central North
Dakota. Stagonospora nodorum
blotch and tan spot, although major
diseases on wheat in North Dakota,
were only isolated at low levels
from barley and are not considered
to be serious problems on barley at
the present time. Because of the
importance of both S. passerinii and
S. avenae f. sp. triticea on barley in
North Dakota, selecting barley for
Septoria/Stagonospora resistance will
require screening with both
pathogens.
The nine isolates of S. nodorum
obtained from barley consistently
produced higher symptom severity,
as measured by percentage
necrosis, on wheat than on barley.
Overall, Fortuna averaged 28%
necrosis and Eureka averaged 29%
necrosis, compared to less than 1%
for Bowman and Hector.
Acknowledgments
The authors thank D. Wetch for
technical assistance, as well as D.E.
Mathre and M. Babadoost for their
reviews and constructive
comments.
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References
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